Recently many extracts and their derivatives oriented from natural plants, such as a vincristinem and a vinbalstine, a camptothecin, a taxol and its derivatives, a palitaxel and a docetaxel, have been widely used in clinical chemical therapy of a malignant tumor. Therefore, the effect of the extracts from natural plants has been a burgeoning research in the field of new drug development.
Flavonoids are widely distributed in plants fulfilling many functions including producing yellow or red/blue pigmentation in flowers and protection from attack by microbes and insects. The widespread distribution of flavonoids, their variety and their relatively low toxicity compared to other active plant compounds (for instance alkaloids) mean that many animals, including humans, ingest significant quantities in their diet. Flavonoids have been referred to as “nature's biological response modifiers” because of strong experimental evidence of their ability to modify the body's reaction to allergens, viruses, and carcinogens. They show anti-allergic, anti-inflammatory, anti-microbial and anti-cancer activity. In addition, flavonoids act as powerful antioxidants, providing remarkable protection against oxidative and free radical damage.
As a result, consumers and food manufacturers have become increasingly interested in flavonoids for their medicinal properties, especially their potentially beneficial role in the prevention of cancers and cardiovascular disease. The beneficial effects of fruit, vegetables, and tea or even red wine have been attributed to flavonoid compounds rather than to known nutrients and vitamins. These beneficial effects await further clinical trials in humans.
In view of the above, the inventors of the present invention discover that the crude extracts of Thelypteris torresiana, only produced in Taiwan, have cytotoxic activities to the NUGC and HONE-1 cell lines supported by the experimental data through screening several dozens of natural crude extracts based on the inventors' experience in studying the effect of the extracts from natural plants for a long time. To study in advance, it is discovered that the unique novel flavonoid compounds therein have strong cytotoxic activities to human cancer cells, including liver cancer cells (Hep G2, and Hep 3B), breast cancer cells (MCF-7, MDA-MB-231), and lung cancer cells (A549).